FIG. 7 is a diagram showing the optical system of a conventional projector. As can be seen in FIG. 7 this projector 90 is provided with an illumination optical system 100, a color separating optical system 200, a relay optical system 240, a reflecting mirror 20, two field lenses 300R and 300G, three liquid crystal panels 3108, 310G, and 310B, a dichroic prism 400, and a projection lens 420. The color separating optical system 200 has dichroic mirrors 210 and 212. The relay optical system 240 has reflecting mirrors 252 and 254, an incident side lens 262, a relay lens 264, and a field lens 266.
The projector 90 separates the light that exits from the light source 110 into the three colors of light red, green, and blue by means of the color separating optical system 200. Then each of the three colored light beams are modulated by three liquid crystal panels 3108, 310G, and 310B, and they are synthesized by means of the dichroic prism 400 and the synthesize beam is projected through the projection lens 420 onto the screen S.
The illumination optical system 100 of this projector 90 separates light that exits from the light source 110 into a plurality of luminous fluxes by means of the first lens array 120, and is gathered in the vicinity of the second lens array 130 so that each luminous flux is compiled by the superimposed lens 150 on the liquid crystal panels 310R, 310G, and 310B. By adopting this type of illumination optical system 100, illumination distribution can be unified within the cross-section of luminous flux that exits the light source 110, making it possible for the liquid crystal panels 310R, 310G, and 310B to be irradiated comparatively uniformly with the illumination of light.
FIG. 8 is a diagram showing the cross-sectional structure of the liquid crystal panel used for the liquid crystal panels 3108, 310G, and 310B. As shown in FIG. 8, the liquid crystal panel 310 has a structure where the liquid crystal layer 317 is arranged in the gap between a TFT substrate 311 where a picture element electrode 312 and TFT element 313 are arranged on the surface, and an opposing substrate 314 where a black matrix 315 and a common electrode 316 are arranged on the surface. Further, polarizing plates 318 and 319 are attached to the other surface of the TFT substrate 311 and the other surface of the opposing substrate 314.
The liquid crystal panel 310 can control transmittance in each picture element for the incident light L that enters from the opposing substrate 314 side by controlling the voltage applied between the picture element electrodes 312 and the common electrodes 316 for each picture element by means of the operation of the TFT element 313. However, by the operation of the black matrix 315, the unnecessary leakage of light from parts other than the picture elements can be prevented. Therefore, the liquid crystal panel 310 can function as a light valve with high contrast.
Accordingly, a projector having a high contrast with superior display quality is achieved by using this type of liquid crystal panel 310 that is a high contrast light valve as three liquid crystal panels 3108, 310G, and 310B of the projector 90.
In recent years, liquid crystal panels with increased light utilization efficiency have been realized by effectively using light that is interrupted by the black matrix. In FIG. 9, a cross-sectional structure of this type of liquid crystal panel is shown. As shown in FIG. 9, the liquid crystal panel 320 has basically the same structure as the liquid crystal panel 310 shown in FIG. 8, with the difference that a micro lens 321 is formed on the opposing substrate 314. Therefore, since the liquid crystal panel 320 has the ability to effectively utilize light interrupted by the black matrix through the operation of the micro lens 321, to increase the luminance of the projector in which the liquid crystal panel 320 as is used for the three liquid crystal panels can be improved.
However, the demand is increasing for projectors with further improvements to the color reproducibility (color matching) of the image displayed on a screen.
An object of the present invention is to further improve the color reproducibility of the image displayed on a screen with a projector.